This invention relates to a method for applying a direction-adjusting extension piece in dental implants and to the elements used thereby.
It is known that in dental prosthetics methods exist for permanently connecting dentures to a completely or partially toothless jaw.
The known methods for fixedly connecting dentures to a toothless jaw can, among other things, exist in implanting, after opening the mucosa or mucous membrane, of a cylindrical structure from a bio-compatible material, for instance titanium, in the bone of the upper or lower jaw, whereby this cylinder-shaped structure is completely countersunk in the bone, after which the mucosa or mucous membrane is sewn up and a waiting period of approximately six months is required, in order to allow the bone to grow together, osseo-integrate respectively, with the implanted structure.
After this waiting period, the mucosa or mucous membrane is re-opened at the implant, and a temporary extension piece is screwed in the implant, after which the mucous membrane is sewn up again around this temporary extension piece. Such a temporary extension piece is used for obtaining, during the healing process of the mucous membrane, a correct transmucosal diameter.
After the mucous membrane has healed, the temporary extension piece is replaced with a definitive extension piece with the required length.
Both the temporary and the definitive extension pieces are screwed in along the axis of the implant.
The definitive extension piece is provided occlusally with internal screw threads upon which the proper dentures can be screwed in the direction of the axis of the implant.
The success level of such an osseo-integration is very high and has been accepted scientifically and clinically.
Depending on the quality of the bone, several implants can be applied, thus enabling a bridge structure, for instance in the form of a tooth ring, to be screwed in. In this tooth ring, small holes are provided through which a prosthesis screw is applied for connecting the tooth ring to each implant.
The above applied prosthesis screws are usually screwed tight in the direction of the axis of the extension piece, so that the axis direction of the implant determines the axis direction of the extension piece and thus also the axis direction of the tooth placed thereupon with the prosthesis screw.
The bone quality, the bone volume and the anatomic limitations of the lower and especially upper jaw sometimes force the surgeon to place the implant at a location not corresponding to the natural location of the former tooth position, thus causing afterwards functional, hygienic and aesthetic complications in the prosthetic field.
If the axis direction of the implant is unfavorable, the access for the screw is provided at unwanted places, and the axis direction of the connected dentures will also be unfavorable, thus causing aesthetic problems.
In order to adjust the axis direction of such unfavorably orientated implants, several direction-adjusting extension pieces have been previously proposed.
Among other things, pre-formed and inclined extension pieces are known, which are glued in the implant, having as a disadvantage, however, that a permanent connection is obtained.
Moreover, the height of such inclined extension pieces often causes aesthetic problems.
Also, bendable extension pieces with a thin neck are known, which can be screwed in the implant, however, they have been found to break easily.
Furthermore, deformable or grindable synthetic extension pieces are known, which are cast in metal through a lost wax casting technique, so that an individual extension piece is obtained, which is breakable, however, and usually fits badly in the implant. Moreover, this method is time-consuming and the extension pieces are not reproduceable if a replacement is necessary.
Other known extension pieces are provided with a ball joint which can be locked. These extension pieces present the disadvantage that they are very complex and very breakable due to their small dimensions.
With the known extension pieces the screw thread of the implant has to be reproduced on a working model with printing systems in order to manufacture an individual extension piece, which is also time-consuming, cumbrous and inaccurate due to the lack of visual control.